Electrode materials usable in cutting of metal materials in an oxidizing atmosphere such as fresh air and oxygen atmosphere are limited to only very small part of metal materials such as hafnium and zirconium. Aside from them, there are various electrode materials excellent in conductivity and heat resistance, but they are readily consumed in an oxidizing atmosphere and are not practically usable.
Hafnium and zirconium are extremely expensive and are hard to obtain, and the cutting cost is very high. Recently, in addition to the improvement and diversification of the cutting equipment, automation and robotics are rapidly promoted for the purposes of saving labor cost and mass production, but the development of the cutting equipment is limited by the delay in improvement of the electrode material.